Paper web, generally wound in rolls or coils which can be of considerable size, is currently widely employed in many different fields, and especially in the product packaging field. In particular, for preparing tea bags, a type of coiled paper is used which comprises a layer of filtering paper one side of which is coated with a suitable film which becomes adhesive (tacky) when raised to a given temperature.
To provide a continuous supply of such a web to the packaging machine, apparatus is known which can carry simultaneously two paper coils, one serving to fee the web while the other held in reserve. Such apparatus is equipped with a station at which the trailing edge of the coil being depleted is bonded to the leading edge of the reserve coil, so that the web can be supplied continuously to the packaging machine.
However, in such prior-art apparatus, to enable the tail edge or end of the coil being used to be connected to the leading edge or end of the fresh coil, it is necessary to stop the packaging machine. This represents a functional drawback of considerable importance as well as a potential source of errors or failure seriously affecting the quality of the subsequent package.